Data-driven methods for look up table-free closed-loop antenna impedance tuning

ABSTRACT

According to an embodiment, a method in a closed-loop antenna impedance tuning (CL-AIT) system is provided. The method includes determining whether a transmitted power is above a pre-determined threshold, when the transmitted power is above the pre-determined threshold, determining a bypass input reflection coefficient, determining whether the bypass input reflection coefficient is greater than a bypass threshold, and when the bypass input reflection coefficient is greater than the bypass threshold, determining an optimal tuner code based on a tuner code search algorithm.

PRIORITY

This application is based on and claims priority under 35 U.S.C. §119(e) to U.S. Provisional Patent Application filed on Sep. 9, 2020 andassigned Ser. No. 63/075,987, and to U.S. Provisional Patent Applicationfiled on Sep. 16, 2020 and assigned Ser. No. 63/079,080, the entirecontents of which are incorporated herein by reference.

FIELD

The present disclosure is generally related to closed-loop antennaimpedance tuning (CL-AIT).

BACKGROUND

For radio antenna transmission systems, an impedance mismatch causespower reflection from the antenna and subsequently degrades the overalltransmission efficiency due to the loss in power transferred to theantenna. Therefore, impedance tuning to minimize the impedance mismatchloss plays an important role in mobile devices with the limited powersupply. A task of impedance tuning is tantamount to configuring amatching network (or a tuner) by properly adjusting its componentsincluding switches, capacitors, and inductors.

SUMMARY

According to one embodiment, a method in a CL-AIT system includesdetermining whether a transmitted power is above a pre-determinedthreshold, when the transmitted power is above the pre-determinedthreshold, determining a bypass input reflection coefficient,determining whether the bypass input reflection coefficient is greaterthan a bypass threshold, and when the bypass input reflectioncoefficient is greater than the bypass threshold, determining an optimaltuner code based on a tuner code search algorithm.

According to one embodiment, a CL-AIT system includes a memory and aprocessor configured to determine whether a transmitted power is above apre-determined threshold, when the transmitted power is above thepre-determined threshold, determine a bypass input reflectioncoefficient, determine whether the bypass input reflection coefficientis greater than a bypass threshold, and when the bypass input reflectioncoefficient is greater than the bypass threshold, determine an optimaltuner code based on a tuner code search algorithm.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features, and advantages of certainembodiments of the present disclosure will be more apparent from thefollowing detailed description, taken in conjunction with theaccompanying drawings, in which:

FIG. 1 illustrates a diagram of a CL-AIT system, according to anembodiment;

FIG. 2 illustrates a flowchart showing an operation of a CL-AIT system,according to an embodiment;

FIGS. 3A and 3B illustrate diagrams of transfer function models,according to an embodiment;

FIG. 4 illustrates evolution of features in reinforcement learning (RL)over time, according to an embodiment:

FIG. 5 illustrates a diagram of a CL-AIT system, according to anembodiment;

FIG. 6 illustrates a diagram of a reference tuner model, according to anembodiment;

FIGS. 7A, 7B and 7C illustrate graphs showing performance, according toan embodiment,

FIG. 8 illustrates a flowchart for a method of determining an optimaltuner code, according to an embodiment; and

FIG. 9 illustrates a block diagram of an electronic device in a networkenvironment, according to one embodiment.

DETAILED DESCRIPTION

Hereinafter, embodiments of the present disclosure are described indetail with reference to the accompanying drawings. It should be notedthat the same elements will be designated by the same reference numeralsalthough they are shown in different drawings. In the followingdescription, specific details such as detailed configurations andcomponents are merely provided to assist with the overall understandingof the embodiments of the present disclosure. Therefore, it should beapparent to those skilled in the art that various changes andmodifications of the embodiments described herein may be made withoutdeparting from the scope of the present disclosure. In addition,descriptions of well-known functions and constructions are omitted forclarity and conciseness. The terms described below are terms defined inconsideration of the functions in the present disclosure, and may bedifferent according to users, intentions of the users, or customs.Therefore, the definitions of the terms should be determined based onthe contents throughout this specification.

The present disclosure may have various modifications and variousembodiments, among which embodiments are described below in detail withreference to the accompanying drawings. However, it should be understoodthat the present disclosure is not limited to the embodiments, butincludes all modifications, equivalents, and alternatives within thescope of the present disclosure.

Although the terms including an ordinal number such as first, second,etc. may be used for describing various elements, the structuralelements are not restricted by the terms. The terms are only used todistinguish one element from another element. For example, withoutdeparting from the scope of the present disclosure, a first structuralelement may be referred to as a second structural element. Similarly,the second structural element may also be referred to as the firststructural element. As used herein, the term “and/or” includes any andall combinations of one or more associated items.

The terms used herein are merely used to describe various embodiments ofthe present disclosure but are not intended to limit the presentdisclosure. Singular forms are intended to include plural forms unlessthe context clearly indicates otherwise. In the present disclosure, itshould be understood that the terms “include” or “have” indicateexistence of a feature, a number, a step, an operation, a structuralelement, parts, or a combination thereof, and do not exclude theexistence or probability of the addition of one or more other features,numerals, steps, operations, structural elements, parts, or combinationsthereof.

Unless defined differently, all terms used herein have the same meaningsas those understood by a person skilled in the art to which the presentdisclosure belongs. Terms such as those defined in a generally useddictionary are to be interpreted to have the same meanings as thecontextual meanings in the relevant field of art, and are not to beinterpreted to have ideal or excessively formal meanings unless clearlydefined in the present disclosure.

The electronic device according to one embodiment may be one of varioustypes of electronic devices. The electronic devices may include, forexample, a portable communication device (e.g., a smart phone), acomputer, a portable multimedia device, a portable medical device, acamera, a wearable device, or a home appliance. According to oneembodiment of the disclosure, an electronic device is not limited tothose described above.

The terms used in the present disclosure are not intended to limit thepresent disclosure but are intended to include various changes,equivalents, or replacements for a corresponding embodiment. With regardto the descriptions of the accompanying drawings, similar referencenumerals may be used to refer to similar or related elements. A singularform of a noun corresponding to an item may include one or more of thethings, unless the relevant context clearly indicates otherwise. As usedherein, each of such phrases as “A or B,” “at least one of A and B,” “atleast one of A or B,” “A, B, or C,” “at least one of A, B, and C,” and“at least one of A, B, or C,” may include all possible combinations ofthe items enumerated together in a corresponding one of the phrases. Asused herein, terms such as “=1^(st),” “2nd,” “first,” and “second” maybe used to distinguish a corresponding component from another component,but are not intended to limit the components in other aspects (e.g.,importance or order). It is intended that if an element (e.g., a firstelement) is referred to, with or without the term “operatively” or“communicatively”, as “coupled with,” “coupled to,” “connected with,” or“connected to” another element (e.g., a second element), it indicatesthat the element may be coupled with the other element directly (e.g.,wired), wirelessly, or via a third element.

As used herein, the term “module” may include a unit implemented inhardware, software, or firmware, and may interchangeably be used withother terms, for example, “logic,” “logic block,” “part,” and“circuitry.” A module may be a single integral component, or a minimumunit or part thereof, adapted to perform one or more functions. Forexample, according to one embodiment, a module may be implemented in aform of an application-specific integrated circuit (ASIC).

A CL-AIT system with automatically configurable matching networks isallows compensation of body effects such as hand grip causing changes inantenna load, which is critical for the performance of mobile deviceswith metallic housing, by monitoring changes in antenna impedance andadjusting the tuner configuration accordingly. As opposed toconventional CL-AIT solutions (e.g., based on lookup table (LUT)search), this disclosure provides a data-driven method to configure atuner for CL-AIT.

Configuring the tuner may be equivalent to finding a tuner code. Theoptimal tuner code is determined by solving an optimization problem. Twotypes of cost functions are considered to maximize the instantaneousperformance and the asymptotic performance of CL-AIT, respectively.While the former is cost-efficiently tackled by hill-climbing (HC)algorithms, the latter is addressed under the RL framework. In any case,a parametric model is considered for the cost function learned fromdata. First, disclosed herein is an analytic model to utilize the domainknowledge. Second, disclosed herein is a black box model based on aneural network. Parameters of both models are estimated by solvingnon-linear least squares problems in offline/online fashion.

FIG. 1 illustrates a diagram of a CL-AIT system, according to anembodiment. The CL-AIT 100 includes an antenna 102, an antenna impedancetuner 104, a tuner control algorithm 106, a feedback receiver 108, abi-directional coupler 110, and a radio frequency (RF) printed circuitboard (PCB) 112 connecting the bi-directional coupler 110 and theantenna impedance tuner 104. The antenna impedance tuner 104 is locatedbetween the bi-directional coupler 110 and the antenna 102. The antennaimpedance tuner 104 is configured by a tuner code a (typicallyrepresented in a binary vector) to set up its switches' state and L/Cvalues. The bi-directional coupler 110 is used to couple transmitted andreflected signals to the feedback path. Then, those captured signals areused to compute the AIT metric, which is an indirect measure of theinput reflection coefficient Γ_(in) towards the antenna impedance tuner104, denoted as {hacek over (γ)}_(in). {hacek over (γ)}_(bypass) denotesγ_(in) measured with the default (or bypass) tuner code a_(bypass).According to {hacek over (γ)}_(bypass), a tuner control algorithm 106determines the optimal tuner code a* to maximize the power transferredto the antenna 102.

FIG. 2 illustrates a flowchart showing an operation of a CL-AIT system,according to an embodiment. At 202, the system enables the CL-AIT. At204, the system initializes the CL-AIT. At 206, at time slot t, thesystem determines whether the transmitted power P_(Tx,t) is above thepre-determined threshold ξ_(pow) to guarantee the desiredsignal-to-noise ratio (SNR) of dumped signals and save sufficient powerfor the antenna to work in arbitrary environment. If the transmittedpower P_(Tx,t) is above the pre-determined threshold, then at 208, thesystem enables a feedback receiver, at 210, the system forwards couplerswitching, at 212, the system dumps a forward coupled signal, at 214,the system reverses coupler switching, at 216, the system dumps areverse coupled signal, and at 218, the system disables a feedbackreceiver.

At 220, the system determines {hacek over (γ)}_(bypass,t). At 222, thesystem determines whether |{hacek over (γ)}_(bypass,t)|>ξ_(bypass),where ξ_(bypass) is a bypass threshold determined by the target AITperformance. If |{hacek over (γ)}_(bypass,t)|>ξ_(bypass), at 224, thesystem determines a* from the tuner control algorithm, and at 226, thesystem sets the tuner code as a_(t)=a*. If |{hacek over(γ)}_(bypass,t)|≤ξ_(bypass), at 228, the system sets the tuner code asa_(t)=a_(bypass). At 230, the system may perform a CL-AIT performancemeasure in embodiments utilizing RL, as is described below.

To formulate a problem to find a*, a data-driven cost function needs tobe defined by using CL-AIT metric, {hacek over (γ)}_(in). Γ_(in) andΓ_(bypass) denote the true reflection coefficients at the tuner inputwith arbitrary tuner code a and with a_(bypass), respectively. With theknown topology of the tuner, a conventional solution may consider a costbased on the analytical expression of Γ_(in) with respect to a,Γ_(bypass), and a channel frequency ω. Given Γ_(bypass) and ω, a* can befound as a solution of Equation (1):

$\begin{matrix}{\left( {P\; 1} \right)\mspace{11mu}{{\Gamma_{in}\left( {a,\Gamma_{bypass},\omega} \right)}}} & (1)\end{matrix}$

where

is a set of available tuner codes. Equivalently, the voltage standingwave ratio (VSWR) can be adopted as the cost of (P1). However, there isa mismatch between γ_(in) (or γ_(bypass)) and Γ_(in) (or Γ_(bypass)) dueto the transmission line effect over the RF PCB 112 and other source ofuncertainties in the forward and backward signals at the bi-directionalcoupler. Furthermore, the fact that only {hacek over (γ)}_(in) isavailable in a CL-AIT system justifies the choice of the data-drivencost based on {hacek over (γ)}_(in), not Γ_(in).

FIGS. 3A and 3B illustrate diagrams of transfer function models forγ_(in), according to an embodiment. The transfer function model 302 maybe utilized for analytic modeling or blind modeling, while the transferfunction model 304 may be utilized for the analytic model describedbelow. To find the data-driven cost considering the instantaneousperformance of CL-AIT, learning of a transfer function of γ_(in) isutilized. It is modeled as a function of a, {hacek over (γ)}_(bypass),and ω with unknown generic parameter vector θ. A model of h(⋅; θ) iseither analytically derived by using the domain knowledge of the tuner(e.g., the tuner topology), or blindly modeled (e.g., by using a neuralnetwork). As θ is independent of ω, the memory size to store h(⋅; θ)does not grow with the number of supporting channel frequencies.

For the analytic modeling, h(⋅; θ) is modeled to be a composite functionof {circumflex over (Γ)}_(in)(⋅; θ_(LC)), {circumflex over(Γ)}_(bypass)(⋅; θ_(bypass)), and g(⋅; θ_(in)), where θ_(LC),θ_(bypass), and θ_(in) are model parameters for {circumflex over(Γ)}_(in), Γ _(bypass), and g, respectively, with θ=[θ_(LC)^(T),θ_(bypass) ^(T), θ_(in) ^(T)]^(T), as shown in 304. While{circumflex over (Γ)}_(in)(ω; θ_(LC)) with {circumflex over(Γ)}_(bypass)(⋅; θ_(bypass)) models Γ_(in) at the tuner input, g(⋅;θ_(in)) captures the transformation of Γ_(in) along the RF PCB section112, bi-directional coupler 110, and feedback receiver 108. Thetransformation function g(⋅; θ_(in)) is empirically modeled to includescaling, rotation, and translation of {circumflex over (Γ)}_(in)(⋅;θ_(LC)). Let α_(in)∈

, ϕ_(in)∈

, and b_(in)∈

denote unknown scaling, rotation, and translation parameters, whichdefine θ_(in):=[α_(in), ϕ_(in), b_(in)]^(T). Then, γ_(in) is modeled tobe, as in Equation (2).γ_(in)≈{hacek over (γ)}_(in) =g({circumflex over (Γ)}_(in)(a,{circumflexover (Γ)} _(bypass)({hacek over(γ)}_(bypass);θ_(bypass)),ω;θ_(LC));θ_(in)):=α_(in) exp(jϕ_(in)){circumflex over (Γ)}_(in)(a,{circumflex over (Γ)}_(bypass)({hacek over (γ)}_(bypass);θ_(bypass)),ω;θ_(LC))+b _(in).  (2)

On the other hand, given the topology of the tuner, {circumflex over(Γ)}_(in)(a,{circumflex over (Γ)}_(bypass)({hacek over (γ)}_(bypass);θ_(bypass)), ω; θ_(LC)) is modeled to have the identical form ofΓ_(in)(a,Γ_(bypass), ω) in Equation (1). The difference in the analyticmodel is, the L/C component values in Γ_(in)(a,Γ_(bypass), ω) areassumed to be unknown model parameters in θ_(LC) and estimated fromdata, instead of considering their nominal values available in thespecification of the tuner. This allows capturing of an actual responseof the tuner rather than naively relying on its ideal response, andsubsequently to address uncertainties in hardware of. Since the form of{circumflex over (Γ)}_(in)(ω; θ_(LC)) is tuner-model-specific, theexample in consideration of a reference tuner model is described withrespect to FIG. 6 will be provided. Similar to the modeling of g(ω;θ_(in)), furthermore, it is modeled to be {circumflex over(Γ)}_(bypass)({hacek over (γ)}_(bypass); θ_(bypass))=α_(bypass)⁻¹e^(−jϕ) ^(bypass) ({hacek over (γ)}_(bypass)−b_(bypass)) withθ_(bypass):=[α_(bypass), ϕ_(bypass), b_(bypass)]^(T).

For the blind modeling, θ is simply a neural network parameter, whichwill be determined by a choice of the neural network structure (e.g.,feedforward neural network or convolutional neural network).

For either modeling approach, θ is estimated by solving a non-linearleast squares problem. Given a training dataset {{hacek over(γ)}_(in,n),a_(n),{hacek over (γ)}_(bypass,n), ω_(n)}_(n=1) ^(N), θiteratively solves the problem as in Equation (3):

$\begin{matrix}{{{\min\limits_{\theta}\;{C\mspace{11mu}(\theta)}} = {\sum\limits_{n = 1}^{N}{{{\overset{\Cup}{\gamma}}_{{in},n} - {h\left( {a_{n},{\overset{\Cup}{\gamma}}_{{bypass},n},{\omega_{n};\theta}} \right)}}}^{2}}},} & (3)\end{matrix}$

which can be tackled via gradient-based algorithms in offline/onlinefashion. Examples of the gradient-based solvers include (stochastic)gradient descent, Gauss-Newton, Levenberg-Marquardt, and adaptive moment(ADAM) algorithms.

Once the estimate of θ is obtained, denoted as {circumflex over (θ)}, a*can be found by solving Equation (4):

$\begin{matrix}{{\left( {P\; 1^{\prime}} \right)\mspace{11mu}{{h\left( {a,{\overset{\Cup}{\gamma}}_{bypass},{\omega;\hat{\theta}}} \right)}}},} & (4)\end{matrix}$

which is found by replacing Γ_(in)(a,Γ_(bypass), ω) in Equation (1) withh(a,{hacek over (γ)}_(bypass), ω;{circumflex over (θ)}). Since

is finite, a* can be found in reed manner via exhaustive search.However, it is computational expensive when

is large. To cost-effectively determine a* for given {hacek over(γ)}_(bypass) and ω, an HIC algorithm according to Table 1 s disclosed.A threshold ξ* can be pre-determined from the target performance measurefor the stopping criterion of the algorithm. Recall that the analytictransfer function model of Γ_(in), which is {circumflex over(Γ)}_(in)({hacek over (γ)}_(bypass);{circumflex over (θ)}_(bypass)),ω;{circumflex over (θ)}_(LC)), is also readily available as a byproductof the analytic model of h(ω; θ) (not for the neural network model).Inspired by the conventional cost in Equation (1), then, {circumflexover (Γ)}_(in)(⋅,{circumflex over (Γ)}_(bypass)(⋅;{circumflex over(θ)}_(bypass)),⋅;{circumflex over (θ)}_(LC)) can be used instead of{hacek over (γ)}=h(⋅;{circumflex over (θ)}) for (P1′) in Equation (4),that is, to find a* by solving

$❘{{{\hat{\Gamma}}_{in}\left( {a,{{\hat{\Gamma}}_{bypass}\left( {{\overset{\Cup}{\gamma}}_{bypass};{\hat{\theta}}_{bypass}} \right)},{\omega;{\hat{\theta}}_{LC}}} \right)}.}$

TABLE 1   Input: ω, {hacek over (γ)}_(bypass), h(·; {circumflex over(θ)}), N_(iter), and ξ* Output: a* Initialization Step: Initialize a⁽⁰⁾∈ 

 at random Search Step:    Set i ← 0 for i ≤ N_(iter) and |h(a^((i)),{hacek over (γ)}_(bypass), ω; {circumflex over (θ)})| > ξ* do      Construct 

(a^((i))) including every a ∈ 

 with       XOR(a^((i)), a) = 1       ${{Find}\mspace{14mu} a_{candidate}} = {\arg\;{\min\limits_{\alpha \in {\mathcal{N}{(\alpha^{(i)})}}}{{h\left( {a,\left( \overset{\bigvee}{\gamma} \right)_{bypass},\omega,\hat{\theta}} \right)}}}}$ if |h a_(candidate), {hacek over (γ)}_(bypass), ω; {circumflex over(θ)})| ≤ |h(a^((i)), {hacek over (γ)}_(bypass), ω; {circumflex over(θ)})| Update a^((i+1)) ← a_(candidate)   else Break  end     Set i ←i + 1 end Set a* ← a^((i)) Return a*

The algorithm in Table 1 has low computational complexity, butguarantees locally optimal a* only. To avoid potentially undesirablelocal minima, the system may also adopt a random-restart HC (RRHC)algorithm. This is a meta-algorithm built on the standard HC algorithmin that it conducts a series of HC searches via the standard algorithmin Table 1 with randomly initialized a⁽⁰⁾ at each attempt, until|h(a*,{hacek over (γ)}_(bypass), ω;{circumflex over (θ)})|≤ξ*, or themaximum number of restarts N_(restart) reached.

Alternatively, an RL algorithm may be utilized that considers theoverall flow of CL-AIT operation. With the RL approach, a Markovdecision process (MDP) is defined first as a tuple (

_(ss′) ^(a),

_(ss′) ^(a),β,

₀), where

is a set of states,

is a set of actions,

_(ss′) ^(a) is a transition probability to the next state s′ when actiona is taken at state s,

_(ss′) ^(a) is the stochastic reward function to map the sequence

s, a, s′

to r∈

, β∈(0,1] is the discount factor to balance current and future rewards,and

₀ is the distribution over initial states s₀. In particular,

_(ss′) ^(a), and

_(ss′) ^(a) constitute the model of the MDP. As opposed to conventionalmachine learning, RL is interaction-based learning.

FIG. 4 illustrates evolution of features in RL over time, according toan embodiment. At each time slot t, an agent takes action a_(t) at givenstate s_(t) according to a current policy π:

→

. Then, the agent receives a reward r_(t) and the next state s_(t+1),and updates the current policy accordingly. Upon finding thecorrespondence of key features between CL-AIT and RL as summarized inTable 2, the system checks that the operation of RL is precisely matchedwith that of CL-AIT in FIG. 2. The block for the CL-AIT performancemeasure at 230 in FIG. 2 is utilized under the RL framework.

TABLE 2 [Correspondence of features between RL and CL-AIT] Reinforcementlearning CL-AIT Agent Antenna impedance tuner State s Reflectioncoefficient in bypass {hacek over (γ)}_(bypass) and channel frequency ωAction a Tuner code a Reward r Performance measure: e.g., VSWR⁻¹,−|{hacek over (γ)}_(in)|, total radiated power Policy π A strategy tofind a*

FIG. 5 illustrates a diagram of a CL-AIT system, according to anembodiment. The CL-AIT 500 includes an antenna 502, an antenna impedancetuner 504, a tuner control algorithm 506, a feedback receiver 508, abi-directional coupler 510, and an RF PCB 512. By assuming the reward asr_(t)=−|{hacek over (γ)}_(in,t)|, a diagram for CL-AIT under RL is shownin FIG. 5. A stochastic gradient descent (SGD) update 514 may be appliedto the tuner control algorithm 506, as further described below.

A goal of RL is to learn the optimal policy π* by solving Equation (5):

$\begin{matrix}{{\left( {P\; 2} \right)\mspace{31mu}{\max\limits_{\pi}{V^{\pi}(s)}}},{\forall{s \in \mathcal{S}}}} & (5)\end{matrix}$

where V^(π)(s) is so-termed state value function defined as in Equation(6).

$\begin{matrix}{{V^{\pi}(s)}:={{{\mathbb{E}}\left\lbrack {{{\sum\limits_{t = 0}^{\infty}{\beta^{t}\mathcal{R}_{s_{t}s_{t + 1}}^{\pi{(s_{t})}}}}❘s_{0}} = s} \right\rbrack}.}} & (6)\end{matrix}$

V^(π)(s) captures the asymptotic performance of CL-AIT in the long runby considering the expected sum of discounted rewards. (P2) isessentially equivalent to (P1) when β=0. π* satisfies the Bellmanoptimality, as in Equation (7):

$\begin{matrix}{{V^{*}(s)}:={{V^{\pi^{*}}(s)} = {\max\limits_{a \in \mathcal{A}}{\underset{\underset{= {:{Q^{*}{({s,a})}}}}{︸}}{\sum\limits_{s^{\prime} \in \mathcal{S}}{\mathcal{P}_{{ss}^{\prime}}^{a}\left\lbrack {\mathcal{R}_{{ss}^{\prime}}^{a} + {\beta\; V^{*}\left( s^{\prime} \right)}} \right\rbrack}}{\forall{s \in \mathcal{S}}}}}}} & (7)\end{matrix}$

where is Q*(s,a) is the optimal state-action value function. Due to therecursion in V*(s), π* can be found via dynamic programming (DP), if theMDP is known. π can be represented as a LUT of size |

|×|

| during learning, where the operator |⋅| stands for the cardinality ofa set. However, the MDP model is not known for CL-AIT due to unknown

_(ss′) ^(a) and

_(ss′) ^(a). Furthermore, the memory requirement to store π during thelearning process is demanding since

is continuous and

is large. With the aim of scalability, the RL problem is handled viaapproximate dynamic programming (ADP) to reduce the computationalcomplexity and memory requirement of a solver by dropping dependencywith

.

The theory of MDPs states that the action at state s from the greedypolicy π can be retrieved via Equation (8):

$\begin{matrix}{{{\pi(s)} = {\arg{\max\limits_{a \in \mathcal{A}}{Q^{\pi}\left( {s,a} \right)}}}},{\forall{s \in \mathcal{S}}}} & (8)\end{matrix}$

with the state-action value function Q^(π)(s,a):=

[

_(ss) ₁ ^(a)+Σ_(t=1) ^(∞)β^(t)

_(s) _(t) _(s) _(t+1) ^(π(s) ^(t) ⁾|s₀=s,a₀=a]. Therefore, if Q*(s,a)becomes available, a* can be found via Equation (8) without using theexplicitly stored π*. However, the expectation involved in Q^(π)(s,a)cannot be evaluated due to unknown

_(ss′) ^(a) and

_(ss′) ^(a) for CL-AIT. To bypass this issue, the system learns anapproximate model of Q*(s,a) in sequential manner by using datacollected offline or during CL-AIT operation. {circumflex over (Q)}(s,a;θ) denotes an approximate function of Q^(π)(s,a), which can be modeledvia neural networks with parameter vector θ. ε_(t) denotes the episodedefined as a finite sequence

s₀, a₀, r₀, s₁, a₁, r₁, s₂, . . . , s_(t), a_(t), r_(t)

with s₀˜

₀ collected up to time slot t. Then, θ can be estimated by solvingEquation (9):

$\begin{matrix}{{\left( {P\; 3} \right)\mspace{31mu}{\min\limits_{\theta}{C(\theta)}}}:={\frac{1}{t}{\sum\limits_{{({s_{\tau},a_{\tau}})} \Subset \mathcal{E}_{t}}{\left( {{Q^{+}\left( {s_{\tau},{a_{\tau};\theta^{({t - 1})}}} \right)} - {\hat{Q}\left( {s_{\tau},{a_{\tau};\theta}} \right)}} \right)^{2}.}}}} & (9)\end{matrix}$

where

${Q^{+}\left( {s_{t},{a_{t};\theta}} \right)}:={r_{t} + {\beta{\max\limits_{a^{\prime} \in \mathcal{A}}{\hat{Q}\left( {s_{t + 1},{a^{\prime};\theta}} \right)}}}}$is a target cost-to-go to approximate unavailable true Q^(π)(s_(t),a_(t)). As ε_(t) grows over t, the SGD is adopted to efficiently solve(P3) by minimizing the instantaneous squared error at each time slot t,as in Equation (10):

$\begin{matrix}{{\min\limits_{\theta}{C_{t}(\theta)}}:=\left( {{Q^{+}\left( {s_{t},{a_{t};\theta^{({t - 1})}}} \right)} - {\hat{Q}\left( {s_{t},{a_{t};\theta}} \right)}} \right)^{2}} & (10)\end{matrix}$

where θ^((t)) is the estimate of θ at time slot t. The minimizationproblem in Equation (10) is processed at each time slot t tosequentially estimate θ with the reduced computational complexity,rather than solving (P3) in Equation (9) in batch fashion. The updaterule for θ at time slot t can be found as in Equation (11):θ^((t))←θ^((t−1))−η∇_(θ) C _(t)(θ)|_(θ=θ) _((t−1))   (11)

with a learning rate η>0. The gradient ∇_(θ)C_(t)(θ) can be obtained byusing well-known backpropagation.

N_(ε) denotes the number of episodes. Further, the ε-greedy algorithmwith {circumflex over (Q)}(s,a; θ) is defined, as in Equation (12):

$\begin{matrix}{{\pi^{ɛ}\left( {s;\theta} \right)}:=\left\{ \begin{matrix}{{\arg{\max\limits_{a \in \mathcal{A}}{\hat{Q}\left( {s,{a;\theta}} \right)}}},} & {{w.p.\mspace{14mu} 1} - ɛ} \\{{{UniformRandom}(\mathcal{A})},} & {w.p.\mspace{14mu} ɛ}\end{matrix} \right.} & (12)\end{matrix}$

in order to balance exploration and exploitation during learningprocess. The RL itself actively chooses a at s from π to collect dataand then polish the current π. This interaction is unique in RL comparedto other learning methods, where data is passively given to the learner.This leads to the Q-learning algorithm summarized in Table 3.

TABLE 3 Q-learning algorithm for AIT Input: MDP\{

_(ss) ^(α),

_(ss) ^(α),}, β, ε, N_(ε) and η Output: π* Initialization Step:Initialize θ⁽⁰⁾ at random Learning Step:  for i = 1, ... , N_(ε) do   Initialize s₀ ∈ 

   Find action a₀ = π^(ε) (s₀; θ⁽⁰⁾) in Equation (12)    for t = 1, ..., T do      Take action a_(t), receive r_(t), and observe the next states_(t+1)      $\left. {Q^{+}\left( {s_{t},{a_{t};\theta^{({t - 1})}}} \right)}\leftarrow{r_{t} + {\beta\;{\max\limits_{a^{\prime} \in \mathcal{A}}{\hat{Q}\left( {s_{t + 1},{a^{\prime};\theta^{({t - 1})}}} \right)}}}} \right.$     Set C_(t)(θ) = (Q⁺(s_(t), a_(t); θ^((t−1))) − {circumflex over(Q)}(s_(t), a_(t); θ))²      Compute ∇_(θ)C_(t)(θ) by usingbackpropagation      θ^((t)) ← θ^((t−1)) − η∇_(θ)C_(t)(θ)|_(θ=θ)_((t−1))      Find action a_(t+1) = π^(ε) (s_(t+1); θ^((t))) in Equation(12)      t ← t + 1     end for     Set θ⁽⁰⁾ ← θ^((T))   end for   Set{circumflex over (θ)} ← θ^((T))    π* ← π greedy w.r.t. {circumflex over(Q)}(s, a; {circumflex over (θ)}) Return π*

Other algorithms may be adopted to get a better descent direction ratherthan ∇_(θ)C_(t)(θ), since the SGD might suffer from slow convergence.Examples of those algorithms include Levenberg-Marquardt (LM) andadaptive moment (ADAM) algorithms. Furthermore, the Q-learning algorithmin Table 3 can be extended to the online setup by setting N_(ε)=1 andT→∞, which does not require offline training. Lastly, the HC algorithmsdescribed herein also can be adopted to cast-efficiently perform

$\arg{\max\limits_{a \in \mathcal{A}}{{\hat{Q}\left( {s,{a;\theta}} \right)}.}}$

FIG. 6 illustrates a diagram of a reference tuner model 600, accordingto an embodiment. Synthetic tests were performed to validate thedisclosed algorithms. With the characteristic impedance Z₀=50 (Ω), ω=900(MHz), and a∈{0,1}¹², RF 1135 in FIG. 6 was considered as a referencetuner model 600 with L₁=7.5 (nH), L₂=10 (nH), L₃=7.5 (nH), L₄=4.3 (nH),L₅=5.1 (nH), C₁(a)=(2³×a₅+2²×a₆+2¹×a₇+2⁰×a₈+1)C_(min,1), andC₂(a)=(2³×a₉+2²×a₁₀+2¹×a₁₁+2⁰×a₁₂+1)C_(min,2) withC_(min,1)=C_(min,2)=0.47 (pF).

Given the tuner model, the transfer function of Γ_(in) with respect toa, ω, and Γ_(bypass) was analytically derived as a generative model asin Equation (13).

$\begin{matrix}{\mspace{85mu}{{{\Gamma_{in}\left( {a,\Gamma_{bypass},\omega} \right)} = \frac{{Y_{in}^{- 1}\left( {a,\Gamma_{bypass}} \right)} - Z_{0}}{{Y_{in}^{- 1}\left( {a,\Gamma_{bypass}} \right)} + Z_{0}}},}} & (13) \\{where} & \; \\{{{Y_{in}\left( {a,\Gamma_{bypass}} \right)} = {\frac{1}{j\;\omega\;{L_{1}^{\prime}(a)}} + \frac{1}{j\;{\omega\left( {{L_{2}^{\prime}(a)} + L_{3}} \right)}}}}\left\{ {1 - {\frac{L_{3}^{2}\left( {{Z_{ant}\left( \Gamma_{bypass} \right)} + {j\;\omega\;{L_{5}^{\prime}(a)}}} \right)}{{L_{2}^{\prime}(a)} + L_{3}} \times \left\lbrack {{{Z_{ant}\left( \Gamma_{bypass} \right)}{L_{4}^{\prime}(a)}} + {j\;\omega\;{L_{4}^{\prime}(a)}{L_{5}^{\prime}(a)}} + {{Z_{ant}\left( \Gamma_{bypass} \right)}{L_{5}^{\prime}(a)}} + \mspace{430mu}{L_{3}\left( {{Z_{ant}\left( \Gamma_{bypass} \right)} + {j\;\omega\;{L_{5}^{\prime}(a)}}} \right)}} \right\rbrack^{- 1}}} \right\}^{- 1}} & (14)\end{matrix}$

with L₁′(a):=(a₁/L₁−ω²C₁(a))⁻¹. L₂′(a):=(1−a₂)L₂, L₄′(a):=(1−a₃)L₄, andL₅′(a):=(a₄/L₅−ω²C₂(a))⁻¹, and

$\begin{matrix}{{Z_{ant}\left( \Gamma_{bypass} \right)} = {\frac{1 + \Gamma_{bypass}}{1 - \Gamma_{bypass}}{Z_{0}.}}} & (15)\end{matrix}$

Then, yin was modeled as a scaled and rotated version of Γ_(in), and sodoes γ_(bypass), that is, γ_(in)=α exp(jϕ)Γ_(in)(a,Γ_(bypass), ω) withα=0.9 and ϕ#=50, and γ_(bypass)={tilde over (α)} exp(j{tilde over(ϕ)})Γ_(bypass) with {tilde over (α)}=0.6 and {tilde over (ϕ)}=30. Afterrandomly generating Γ_(bypass), {hacek over (γ)}_(in) and {hacek over(γ)}_(bypass) were found by adding noise to γ_(in) and γ_(bypass),respectively. The performance metric was set to Equation (16) with{tilde over (Γ)}_(bypass)({hacek over (γ)}_(bypass)):={tilde over (α)}⁻¹exp(−j{tilde over (ϕ)}){hacek over (γ)}_(bypass)

$\begin{matrix}{{{VSWR}\left( {a,{\overset{ˇ}{\gamma}}_{bypass},\omega} \right)}:={\frac{1 + {{\Gamma_{in}\left( {a,{{\overset{\sim}{\Gamma}}_{bypass}\left( {\overset{ˇ}{\gamma}}_{bypass} \right)},\omega} \right)}}}{1 - {{\Gamma_{in}\left( {a,{{\overset{\sim}{\Gamma}}_{bypass}\left( {\overset{ˇ}{\gamma}}_{bypass} \right)},\omega} \right)}}}.}} & (16)\end{matrix}$

For the algorithms described herein, h(a,{hacek over (γ)}_(bypass), ω;θ) via analytic modeling particularly considered

$\begin{matrix}{{{{\hat{\Gamma}}_{in}\left( {a,{{\hat{\Gamma}}_{bypass}\left( {{\overset{ˇ}{\gamma}}_{bypass};\theta_{bypass}} \right)},{\omega;\theta_{LC}}} \right)} = \frac{{{\hat{Y}}_{in}^{- 1}\left( {a,{{\hat{\Gamma}}_{bypass}\left( {{\overset{ˇ}{\gamma}}_{bypass};\theta_{bypass}} \right)},{\omega;\theta_{LC}}} \right)} - Z_{0}}{{{\hat{Y}}_{in}^{- 1}\left( {a,{{\hat{\Gamma}}_{bypass}\left( {{\overset{ˇ}{\gamma}}_{bypass};\theta_{bypass}} \right)},{\omega;\theta_{LC}}} \right)} + Z_{0}}},} & (17) \\{where} & \; \\{{{{\hat{Y}}_{in}\left( {a,{{\hat{\Gamma}}_{bypass}\left( {{\overset{ˇ}{\gamma}}_{bypass};\theta_{bypass}} \right)},{\omega;\theta_{LC}}} \right)} = {\frac{1}{j\;\omega\;{L_{1}^{\prime}(a)}} + \frac{1}{j\;{\omega\left( {{L_{2}^{\prime}(a)} + L_{3}} \right)}}}}\mspace{194mu}\left\{ {1 - {\frac{L_{3}^{2}\left( {{Z_{ant}\left( {{\hat{\Gamma}}_{bypass}\left( {{\overset{ˇ}{\gamma}}_{bypass};\theta_{bypass}} \right)} \right)} + {j\;\omega\;{L_{3}^{\prime}(a)}}} \right)}{{L_{2}^{\prime}(a)} + L_{3}} \times \mspace{175mu}\left\lbrack {{{Z_{ant}\left( {{\hat{\Gamma}}_{bypass}\left( {{\overset{ˇ}{\gamma}}_{bypass};\theta_{bypass}} \right)} \right)}{L_{4}^{\prime}(a)}} + {j\;\omega\;{L_{4}^{\prime}(a)}{L_{5}^{\prime}(a)}} + \mspace{371mu}{{Z_{ant}\left( {{\hat{\Gamma}}_{bypass}\left( {{\overset{ˇ}{\gamma}}_{bypass};\theta_{bypass}} \right)} \right)}{L_{5}^{\prime}(a)}} + {L_{3}\left( {{Z_{ant}\left( {{\hat{\Gamma}}_{bypass}\left( {{\overset{ˇ}{\gamma}}_{bypass};\theta_{bypass}} \right)} \right)} + {j\;\omega\;{L_{5}^{\prime}(a)}}} \right)}} \right\rbrack^{- 1}}} \right\}^{- 1}} & (18)\end{matrix}$

with θ_(LC)=[L₁, L₂, L₃, L₄, L₅, C_(min,1), C_(min,2)]^(T) andZ_(ant)(⋅) in Equation (15). The model of {circumflex over(Γ)}_(in)(a,{circumflex over (Γ)}_(bypass)({hacek over (γ)}_(bypass);θ_(bypass)), ω; θ_(LC)) in Equation (18) has the identical form ofΓ_(in)(a,Γ_(bypass), ω) in Equation (13), but the L/C component valuesin θ_(LC) are estimated rather than considering their nominal values.

h(a,{hacek over (γ)}_(bypass), ω; θ) via blind modeling and {circumflexover (Q)}(s,a; θ) were modeled by using feedforward neural networks with3 and 2 hidden layers, respectively, having 30 nodes per layer withrectified linear unit (ReLU) activation functions, while the outputlayer considered the pure linear activation functions.

After estimating θ via the LM for the analytic model and the ADAM forthe neural network (blind) model, respectively, in an offline manner,the CL-AIT algorithms were tested over a set of randomly generatedmeasurements of {hacek over (γ)}_(bypass). For HC algorithms, it was setto N_(iter)=20 and N_(restart)=34. For the Q-learning algorithm, adeterministic reward function is set as

_(ss′) ^(a):=VSWR⁻¹(a,{hacek over (γ)}_(bypass), ω), and subsequently,r_(t)=VSWR⁻¹(a_(t),{hacek over (γ)}_(bypass,t), ω). Furthermore, β=10⁻³was set to mainly focus on the instantaneous reward. For ε-greedypolicy, the epsilon-first strategy was particularly considered, that is,as in Equation (19).

$\begin{matrix}{{\pi^{ɛ}\left( {s;\theta} \right)}:=\left\{ {\begin{matrix}{{{UniformRandom}(\mathcal{A})},} & {{{for}\mspace{14mu} t} \leq {ɛ\; T}} \\{{\arg{\max\limits_{a}{\hat{Q}\left( {s,{a;\theta}} \right)}}},} & {{{for}\mspace{14mu} t} > {ɛ\; T}}\end{matrix}.} \right.} & (19)\end{matrix}$

With such a policy, only the exploration phase occurs for first εT timeslots, and only the exploitation phase follows for remaining (1−ε)T timeslots. For simulated tests, it was set to ε=0.4 to sufficiently explorelarge

. Then, a* was found from

$\arg{\max\limits_{a}{\hat{Q}\left( {s,{a;\theta}} \right)}}$via exhaustive search (ES). ES was performed to find

$\min\limits_{a}{{VSWR}\left( {a,{\overset{ˇ}{\gamma}}_{bypass},\omega} \right)}$and a LUT with 24 reference load points were considered as competingalternatives. ES is not practical, but shows the performance limit.

FIGS. 7A, 7B, and 7C illustrate graphs 700, 702 and 706 showingperformance, according to an embodiment. FIGS. 7A-7C show the empiricalcumulative distribution functions (CDFs) of VSWR after impedance tuning,achieved by the methods and competing alternatives. Both standard HC andRRHC with the analytic model outperformed LUT. In particular, RRHCshowed the performance comparable to ES. For the blind model with theneural network, while the standard HC algorithm performed worse thanLUT, the RRHC outperformed LUT and was comparable to ES similar to thecase of the analytic model. This infers the existence of undesirablelocal minima, and the random-restart strategy helps the standard HCalgorithm to avoid those points. As explained above, the RL problem (P2)in Equation (3) is approximately equivalent to (P1) in Equation (1) bysetting β≈0. Therefore, the Q-learning algorithm performed similar tothe RRHC, while RL relied only on the data without using any domainknowledge. The performance of the RL approach comes with highercomputational complexity than HC algorithms. As |

|=2¹² for the reference tuner 600 in FIG. 6, the complexity is mainlydue to finding greedy actions a′ to obtain Q⁺ and a_(t+1), whichcomplexity is in the order of

(|

|), at each time slot t. For this preliminary test, the per-time slotelapsed time was 5×10⁻³ (sec) on average with N_(ε)=30 and T=5×10³ forQ-learning in Table 3. One may adopt the HC algorithms to find a′ anda_(t+1) with reduced complexity. A more fundamental solution to jointlyhandle large state space

and action space

may be utilized.

The systems and methods disclosed herein outperformed the LUT search forCL-AIT, while addressing practical issues of CL-AIT such as {hacek over(γ)}_(bypass)≠Γ_(bypass) (or {hacek over (γ)}_(in)≠Γ_(in)) and theimperfectness of hardware with the help of data-driven learningtechniques.

The systems and methods use the cost function learned from data, notderived based on ideal response of the tuner, to find the optimal tunercode. The methods are LUT-free methods. As such, the memory requirementdoes not linearly grow with the number of channel frequencies tosupport, while a LUT-based solution does. Instead, the memoryrequirement depends on the size of the model parameter for the costfunction, which is independent of the number of channel frequencies. Dueto the availability of online algorithms, offline calibration is notnecessarily required, and the model can adapt to newly collected dataduring CL-AIT operation. Conventionally, a cost function is found basedon ideal response of the given configuration of the tuner. In practice,however, there is a mismatch between actual and ideal responses of thetuner due to uncertainties in hardware. This eventually degrades theefficacy of such cost. On the other hand, the data-driven cost functionstake these uncertainties into account by fitting the cost function modelto data collected from a device to operate CL-AIT. As the CL-AIToperates based on the sequential decision making, the reinforcementlearning framework fits well on a CL-AIT task.

FIG. 8 illustrates a flowchart 800 for a method of determining anoptimal tuner code, according to an embodiment. At 802, the systeminitializes a CL-AIT system. At 804, the system determines whether atransmitted power is above a pre-determined threshold. At 806, when thetransmitted power is above the pre-determined threshold, the systemdetermines a bypass input reflection coefficient. At 808, the systemdetermines whether the bypass input reflection coefficient is greaterthan a bypass threshold. At 810, when the bypass input reflectioncoefficient is greater than the bypass threshold, the system determinesan optimal tuner code based on a tuner code search algorithm. The tunercode search algorithm may be an HC algorithm or an RL algorithm.

FIG. 9 illustrates a block diagram of an electronic device 901 in anetwork environment 900, according to one embodiment. Referring to FIG.9, the electronic device 901 in the network environment 900 maycommunicate with an electronic device 902 via a first network 998 (e.g.,a short-range wireless communication network), or an electronic device904 or a server 908 via a second network 999 (e.g., a long-rangewireless communication network). The electronic device 901 maycommunicate with the electronic device 904 via the server 908. Theelectronic device 901 may include a processor 920, a memory 930, aninput device 950, a sound output device 955, a display device 960, anaudio module 970, a sensor module 976, an interface 977, a haptic module979, a camera module 980, a power management module 988, a battery 989,a communication module 990, a subscriber identification module (SIM)996, or an antenna module 997. In one embodiment, at least one (e.g.,the display device 960 or the camera module 980) of the components maybe omitted from the electronic device 901, or one or more othercomponents may be added to the electronic device 901. In one embodiment,some of the components may be implemented as a single integrated circuit(IC). For example, the sensor module 976 (e.g., a fingerprint sensor, aniris sensor, or an illuminance sensor) may be embedded in the displaydevice 960 (e.g., a display).

The processor 920 may execute, for example, software (e.g., a program940) to control at least one other component (e.g., a hardware or asoftware component) of the electronic device 901 coupled with theprocessor 920, and may perform various data processing or computations.As at least part of the data processing or computations, the processor920 may load a command or data received from another component (e.g.,the sensor module 976 or the communication module 990) in volatilememory 932, process the command or the data stored in the volatilememory 932, and store resulting data in non-volatile memory 934. Theprocessor 920 may include a main processor 921 (e.g., a centralprocessing unit (CPU) or an application processor (AP)), and anauxiliary processor 923 (e.g., a graphics processing unit (GPU), animage signal processor (ISP), a sensor hub processor, or a communicationprocessor (CP)) that is operable independently from, or in conjunctionwith, the main processor 921. Additionally or alternatively, theauxiliary processor 923 may be adapted to consume less power than themain processor 921, or execute a particular function. The auxiliaryprocessor 923 may be implemented as being separate from, or a part of,the main processor 921.

The auxiliary processor 923 may control at least some of the functionsor states related to at least one component (e.g., the display device960, the sensor module 976, or the communication module 990) among thecomponents of the electronic device 901, instead of the main processor921 while the main processor 921 is in an inactive (e.g., sleep) state,or together with the main processor 921 while the main processor 921 isin an active state (e.g., executing an application). According to oneembodiment, the auxiliary processor 923 (e.g., an image signal processoror a communication processor) may be implemented as part of anothercomponent (e.g., the camera module 980 or the communication module 990)functionally related to the auxiliary processor 923.

The memory 930 may store various data used by at least one component(e.g., the processor 920 or the sensor module 976) of the electronicdevice 901. The various data may include, for example, software (e.g.,the program 940) and input data or output data for a command relatedthereto. The memory 930 may include the volatile memory 932 or thenon-volatile memory 934.

The program 940 may be stored in the memory 930 as software, and mayinclude, for example, an operating system (OS) 942, middleware 944, oran application 946.

The input device 950 may receive a command or data to be used by othercomponent (e.g., the processor 920) of the electronic device 901, fromthe outside (e.g., a user) of the electronic device 901. The inputdevice 950 may include, for example, a microphone, a mouse, or akeyboard.

The sound output device 955 may output sound signals to the outside ofthe electronic device 901. The sound output device 955 may include, forexample, a speaker or a receiver. The speaker may be used for generalpurposes, such as playing multimedia or recording, and the receiver maybe used for receiving an incoming call. According to one embodiment, thereceiver may be implemented as being separate from, or a part of, thespeaker.

The display device 960 may visually provide information to the outside(e.g., a user) of the electronic device 901. The display device 960 mayinclude, for example, a display, a hologram device, or a projector andcontrol circuitry to control a corresponding one of the display,hologram device, and projector. According to one embodiment, the displaydevice 960 may include touch circuitry adapted to detect a touch, orsensor circuitry (e.g., a pressure sensor) adapted to measure theintensity of force incurred by the touch.

The audio module 970 may convert a sound into an electrical signal andvice versa. According to one embodiment, the audio module 970 may obtainthe sound via the input device 950, or output the sound via the soundoutput device 955 or a headphone of an external electronic device 902directly (e.g., wired) or wirelessly coupled with the electronic device901.

The sensor module 976 may detect an operational state (e.g., power ortemperature) of the electronic device 901 or an environmental state(e.g., a state of a user) external to the electronic device 901, andthen generate an electrical signal or data value corresponding to thedetected state. The sensor module 976 may include, for example, agesture sensor, a gyro sensor, an atmospheric pressure sensor, amagnetic sensor, an acceleration sensor, a grip sensor, a proximitysensor, a color sensor, an infrared (IR) sensor, a biometric sensor, atemperature sensor, a humidity sensor, or an illuminance sensor.

The interface 977 may support one or more specified protocols to be usedfor the electronic device 901 to be coupled with the external electronicdevice 902 directly (e.g., wired) or wirelessly. According to oneembodiment, the interface 977 may include, for example, a highdefinition multimedia interface (HDMI), a universal serial bus (USB)interface, a secure digital (SD) card interface, or an audio interface.

A connecting terminal 978 may include a connector via which theelectronic device 901 may be physically connected with the externalelectronic device 902. According to one embodiment, the connectingterminal 978 may include, for example, an HDMI connector, a USBconnector, an SD card connector, or an audio connector (e.g., aheadphone connector).

The haptic module 979 may convert an electrical signal into a mechanicalstimulus (e.g., a vibration or a movement) or an electrical stimuluswhich may be recognized by a user via tactile sensation or kinestheticsensation. According to one embodiment, the haptic module 979 mayinclude, for example, a motor, a piezoelectric element, or an electricalstimulator.

The camera module 980 may capture a still image or moving images.According to one embodiment, the camera module 980 may include one ormore lenses, image sensors, image signal processors, or flashes.

The power management module 988 may manage power supplied to theelectronic device 901. The power management module 988 may beimplemented as at least part of, for example, a power managementintegrated circuit (PMIC).

The battery 989 may supply power to at least one component of theelectronic device 901. According to one embodiment, the battery 989 mayinclude, for example, a primary cell which is not rechargeable, asecondary cell which is rechargeable, or a fuel cell.

The communication module 990 may support establishing a direct (e.g.,wired) communication channel or a wireless communication channel betweenthe electronic device 901 and the external electronic device (e.g., theelectronic device 902, the electronic device 904, or the server 908) andperforming communication via the established communication channel. Thecommunication module 990 may include one or more communicationprocessors that are operable independently from the processor 920 (e.g.,the AP) and supports a direct (e.g., wired) communication or a wirelesscommunication. According to one embodiment, the communication module 990may include a wireless communication module 992 (e.g., a cellularcommunication module, a short-range wireless communication module, or aglobal navigation satellite system (GNSS) communication module) or awired communication module 994 (e.g., a local area network (LAN)communication module or a power line communication (PLC) module). Acorresponding one of these communication modules may communicate withthe external electronic device via the first network 998 (e.g., ashort-range communication network, such as Bluetooth™, wireless-fidelity(Wi-Fi) direct, or a standard of the Infrared Data Association (IrDA))or the second network 999 (e.g., a long-range communication network,such as a cellular network, the Internet, or a computer network (e.g.,LAN or wide area network (WAN)). These various types of communicationmodules may be implemented as a single component (e.g., a single IC), ormay be implemented as multiple components (e.g., multiple ICs) that areseparate from each other. The wireless communication module 992 mayidentify and authenticate the electronic device 901 in a communicationnetwork, such as the first network 998 or the second network 999, usingsubscriber information (e.g., international mobile subscriber identity(IMSI)) stored in the subscriber identification module 996.

The antenna module 997 may transmit or receive a signal or power to orfrom the outside (e.g., the external electronic device) of theelectronic device 901. According to one embodiment, the antenna module997 may include one or more antennas, and, therefrom, at least oneantenna appropriate for a communication scheme used in the communicationnetwork, such as the first network 998 or the second network 999, may beselected, for example, by the communication module 990 (e.g., thewireless communication module 992). The signal or the power may then betransmitted or received between the communication module 990 and theexternal electronic device via the selected at least one antenna.

At least some of the above-described components may be mutually coupledand communicate signals (e.g., commands or data) therebetween via aninter-peripheral communication scheme (e.g., a bus, a general purposeinput and output (GPIO), a serial peripheral interface (SPI), or amobile industry processor interface (MIPI)).

According to one embodiment, commands or data may be transmitted orreceived between the electronic device 901 and the external electronicdevice 904 via the server 908 coupled with the second network 999. Eachof the electronic devices 902 and 904 may be a device of a same type as,or a different type, from the electronic device 901. All or some ofoperations to be executed at the electronic device 901 may be executedat one or more of the external electronic devices 902, 904, or 908. Forexample, if the electronic device 901 should perform a function or aservice automatically, or in response to a request from a user oranother device, the electronic device 901, instead of, or in additionto, executing the function or the service, may request the one or moreexternal electronic devices to perform at least part of the function orthe service. The one or more external electronic devices receiving therequest may perform the at least part of the function or the servicerequested, or an additional function or an additional service related tothe request, and transfer an outcome of the performing to the electronicdevice 901. The electronic device 901 may provide the outcome, with orwithout further processing of the outcome, as at least part of a replyto the request. To that end, a cloud computing, distributed computing,or client-server computing technology may be used, for example.

One embodiment may be implemented as software (e.g., the program 940)including one or more instructions that are stored in a storage medium(e.g., internal memory 936 or external memory 938) that is readable by amachine (e.g., the electronic device 901). For example, a processor ofthe electronic device 901 may invoke at least one of the one or moreinstructions stored in the storage medium, and execute it, with orwithout using one or more other components under the control of theprocessor. Thus, a machine may be operated to perform at least onefunction according to the at least one instruction invoked. The one ormore instructions may include code generated by a complier or codeexecutable by an interpreter. A machine-readable storage medium may beprovided in the form of a non-transitory storage medium. The term“non-transitory” indicates that the storage medium is a tangible device,and does not include a signal (e.g., an electromagnetic wave), but thisterm does not differentiate between where data is semi-permanentlystored in the storage medium and where the data is temporarily stored inthe storage medium.

According to one embodiment, a method of the disclosure may be includedand provided in a computer program product. The computer program productmay be traded as a product between a seller and a buyer. The computerprogram product may be distributed in the form of a machine-readablestorage medium (e.g., a compact disc read only memory (CD-ROM)), or bedistributed (e.g., downloaded or uploaded) online via an applicationstore (e.g., Play Store™), or between two user devices (e.g., smartphones) directly. If distributed online, at least part of the computerprogram product may be temporarily generated or at least temporarilystored in the machine-readable storage medium, such as memory of themanufacturer's server, a server of the application store, or a relayserver.

According to one embodiment, each component (e.g., a module or aprogram) of the above-described components may include a single entityor multiple entities. One or more of the above-described components maybe omitted, or one or more other components may be added. Alternativelyor additionally, a plurality of components (e.g., modules or programs)may be integrated into a single component. In this case, the integratedcomponent may still perform one or more functions of each of theplurality of components in the same or similar manner as they areperformed by a corresponding one of the plurality of components beforethe integration. Operations performed by the module, the program, oranother component may be carried out sequentially, in parallel,repeatedly, or heuristically, or one or more of the operations may beexecuted in a different order or omitted, or one or more otheroperations may be added.

Although certain embodiments of the present disclosure have beendescribed in the detailed description of the present disclosure, thepresent disclosure may be modified in various forms without departingfrom the scope of the present disclosure. Thus, the scope of the presentdisclosure shall not be determined merely based on the describedembodiments, but rather determined based on the accompanying claims andequivalents thereto.

What is claimed is:
 1. A method in a closed-loop antenna impedancetuning (CL-AIT) system, comprising: determining whether a transmittedpower is above a pre-determined threshold; when the transmitted power isabove the pre-determined threshold, determining a bypass inputreflection coefficient; determining whether the bypass input reflectioncoefficient is greater than a bypass threshold by directly comparing thebypass input reflection coefficient and the bypass threshold; and whenthe bypass input reflection coefficient is greater than the bypassthreshold, determining an optimal tuner code based on a tuner codesearch algorithm.
 2. The method of claim 1, wherein the tuner searchcode algorithm comprises a hill-climbing (HC) algorithm.
 3. The methodof claim 2, further comprising determining a transfer function model. 4.The method of claim 3, wherein the transfer function model is determinedanalytically based on tuner topology.
 5. The method of claim 3, whereinthe transfer function model is determined blindly based on at least oneneural network.
 6. The method of claim 1, wherein the tuner search codealgorithm comprises a reinforcement learning (RL) algorithm.
 7. Themethod of claim 6, further comprising performing a CL-AIT performancemeasurement.
 8. The method of claim 6, the RL algorithm compriseslearning an optimal policy to determine the optimal tuner code.
 9. Themethod of claim 8, wherein the RL algorithm comprises determining anoptimal state-action value function.
 10. The method of claim 6, whereinthe RL algorithm utilizes approximate dynamic programming (ADP).
 11. Aclosed-loop antenna impedance tuning (CL-AIT) system, comprising: amemory; and a processor configured to: determine whether a transmittedpower is above a pre-determined threshold; when the transmitted power isabove the pre-determined threshold, determine a bypass input reflectioncoefficient; determine whether the bypass input reflection coefficientis greater than a bypass threshold by directly comparing the bypassinput reflection coefficient and the bypass threshold; and when thebypass input reflection coefficient is greater than the bypassthreshold, determine an optimal tuner code based on a tuner code searchalgorithm.
 12. The system of claim 11, wherein the tuner search codealgorithm comprises a hill-climbing (HC) algorithm.
 13. The system ofclaim 12, wherein the processor is further configured to determine atransfer function model.
 14. The system of claim 13, the transferfunction model is determined analytically based on tuner topology. 15.The system of claim 13, wherein the transfer function model isdetermined blindly based on at least one neural network.
 16. The systemof claim 11, wherein the tuner search code algorithm comprises areinforcement learning (RL) algorithm.
 17. The system of claim 16,wherein the processor is further configured to perform a CL-AITperformance measurement.
 18. The system of claim 16, the RL algorithmcomprises learning an optimal policy to determine the optimal tunercode.
 19. The system of claim 18, wherein the RL algorithm comprisesdetermining an optimal state-action value function.
 20. The system ofclaim 16, wherein the RL algorithm utilizes approximate dynamicprogramming (ADP).